1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
/*
* Tree search generalized from Knuth (6.2.2) Algorithm T just like
* the AT&T man page says.
*
* The node_t structure is for internal use only, lint doesn't grok it.
*
* Written by reading the System V Interface Definition, not the code.
*
* Totally public domain.
*/
/*LINTLIBRARY*/
#include "tsearch.h"
#include <stdlib.h>
typedef struct node_t {
char *key;
struct node_t *left, *right;
} node;
/* find or insert datum into search tree */
void *
tsearch(const void *vkey, void **vrootp,
int (*compar)(const void *, const void *))
{
node *q;
char *key = (char *)vkey;
node **rootp = (node **)vrootp;
if (rootp == (struct node_t **)0)
return ((void *)0);
while (*rootp != (struct node_t *)0) { /* Knuth's T1: */
int r;
if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
return ((void *)*rootp); /* we found it! */
rootp = (r < 0) ?
&(*rootp)->left : /* T3: follow left branch */
&(*rootp)->right; /* T4: follow right branch */
}
q = (node *) malloc(sizeof(node)); /* T5: key not found */
if (q != (struct node_t *)0) { /* make new node */
*rootp = q; /* link new node to old */
q->key = key; /* initialize new node */
q->left = q->right = (struct node_t *)0;
}
return ((void *)q);
}
/* find datum in search tree */
void *
tfind(const void *vkey, void **vrootp,
int (*compar)(const void *, const void *))
{
char *key = (char *)vkey;
node **rootp = (node **)vrootp;
if (rootp == (struct node_t **)0)
return ((void *)0);
while (*rootp != (struct node_t *)0) { /* Knuth's T1: */
int r;
if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
return ((void *)*rootp); /* we found it! */
rootp = (r < 0) ?
&(*rootp)->left : /* T3: follow left branch */
&(*rootp)->right; /* T4: follow right branch */
}
return ((void *)0); /* T5: key not found */
}
/* delete node with given key */
void *
tdelete(const void *vkey, void **vrootp,
int (*compar)(const void *, const void *))
{
node **rootp = (node **)vrootp;
char *key = (char *)vkey;
node *p = (node *)1;
node *q;
node *r;
int cmp;
if (rootp == (struct node_t **)0 || *rootp == (struct node_t *)0)
return ((struct node_t *)0);
while ((cmp = (*compar)(key, (*rootp)->key)) != 0) {
p = *rootp;
rootp = (cmp < 0) ?
&(*rootp)->left : /* follow left branch */
&(*rootp)->right; /* follow right branch */
if (*rootp == (struct node_t *)0)
return ((void *)0); /* key not found */
}
r = (*rootp)->right; /* D1: */
if ((q = (*rootp)->left) == (struct node_t *)0) /* Left (struct node_t *)0? */
q = r;
else if (r != (struct node_t *)0) { /* Right link is null? */
if (r->left == (struct node_t *)0) { /* D2: Find successor */
r->left = q;
q = r;
} else { /* D3: Find (struct node_t *)0 link */
for (q = r->left; q->left != (struct node_t *)0; q = r->left)
r = q;
r->left = q->right;
q->left = (*rootp)->left;
q->right = (*rootp)->right;
}
}
free((struct node_t *) *rootp); /* D4: Free node */
*rootp = q; /* link parent to new node */
return(p);
}
|
